Turn FR into bike meter

[Al Johnson]

On Friday 03 July 2009, arne anka wrote:
> >> Hm, i was always under the impression that most bike systems use a
> >> simple magnet and a reed switch (no need for hall effect sensor) for
> >> both cadence and speed measurements. So any sensor from a regular
> >> "bike computer" can be directly attached to the mic line of FR.
> >
> > They do, and they eventually fail
>
> how?

The same as any other mechanical switch - operation becomes unreliable leading 
to inaccurate speed measurement, then fails completely. It doesn't happen 
quickly - it was on the second or third set of batteries so it would have been 
several years and thousands of miles.